Electric circuit breaker



Sent. 26, 1933. w B. WHITNEY Er Al.

ELECTRIC CIRCUIT BREAKER Filed`April l, 1927 3 Sheets-Sheet 1 'Ilillllltlllllillll Sept. .26, 1933. w B WHn-NEY ET AL I 1,928,470

ELECTRIC CIRCUIT BREAK-ER FiledApril 1, 1927 3 sheets-sheet 2 a, ll

Sept. 26, 1933. l w. la;` WHITNEY ET A1. 1,928,470

ELECTRIC C IRGUIT BREAKBR F1ed`April l. 1927 3 Sheets-Sheet 3 www5 Patented Sept. 26, 1933 l ELECTRIC `CIRCUIT BnEAxEn .Willis Bevan Whitney and Edmund Basil Wedmore, London,

England, assignors to The British Electrical and Allied Industries Research-(Association, London, England, aBritish association Application April 1, 1927, serial No. 180,204, and in Great Britain April 1o,` 192s 16 Claims.

'Ihis invention concerns improvements in or relating to electric circuit-breakers, such as switches, fuses, lightning arrestors and the like and it is particularly applicable to, although not limited to, circuit-breakers adapted for use in high tension power circuits say of 10,000 K. if. A. and upwards.

The general object of the present invention is to improve devices of the above character in such manner that the arc set up by or in them is quenched as quickly as possible and with a minimum release of energy in thearc.

It would appear that one of the points that have to be considered in the design of a circuitbreaker is the tendency for hot gases to collect and remain in the neighbourhood of the arc root where, by hindering the cooling of the contact or electrode, they tend to prevent rapid quenching of the arc, and an object of the present inventionris to provide for the rapid disposal of such hot gases and yet minimize lengthening of the arc in the quenching operation beyond the length to which `it is drawn by the separation of the electrodes.

We are aware that it has been proposed heretofore to employ tubular electrodes through which hot gases emanating fromfthe arc may escape; to enclose these electrodes in a gas-tight chamber; and to initiate compression of gas in such chamber prior to separation of the electrodes to break the circuit of which they form part.

A feature of the present invention is an electric circuit-breaker for use with alternating current (having, for example, electrodes of the male and female type) wherein one electrode forms or constitutes a passage .or a portion thereof and is so arranged in relation to the companion electrode that the arc can be quenched by permitting the rapid escape of, or causing the removal of, hot gases from the vicinity of the arc-root and arc-path along said passage which passage is so dimensioned in relation to the cross-section of -inafter, the dimension of the said passage shouldl i not materially exceed a dimension of the order of twice the diameter of an arc crater or burn formed by an arc between contacts during a whole 5 cycle of arcing.

The arc cannot extend along the passage without becoming short-circuited; this short circuitingofpartofthe arcbeing due tothefact thatT (Cl. 20o-148) the wall of the passage (or the portion thereof constituted by the electrode) presents substantially an equipotential surface which will shortcircuit the portion of the arc extending between the arc-root and another part of the arc that may happen to engage that surface. Preferably, the dimension of the passage in relation to-the cross-section of the arc is such that, not only 1s looping of the arc prevented as aforesaid but any attempt of the arc-root to creep into the passage will be frustrated by the arc engaging .the passage wall thereby short-circuiting the part of the arc that has succeeded in'entering the passage, and returning the arc-root to or near its initial position at the passage mouth.

The passage aforesaid should, for the best results, be so dimensioned and/or arranged as to ensure that there is no material increase in any pressure tending to oppose the escape of the hot gases after the arc is established.

A further feature of the invention is the pro- -vision in an electric circuit-breaker for use with alternating current (having, for example, electrodes of the male and female type) in which arcs are quenched by the removal of hot gases from the vicinity of the arc-root and arc-path along a passage or the like of means for establishing over the arc-bearing surfaces of the electrodes and in the general direction of the arc axis a uni-directional flow of a gas or gases (for example, hydrogen or air, or an inert gas such as argon, nitrogen, helium, or the like), and guiding means whereby the entire arc throughout the arcingl period is compelled to remain within the gas stream thus established.

The invention comprises also as a feature an electric circuit-breaker for use with alternating current (having, for example, electrodes of the male and female type) wherein one electrode forms or constitutes afpassage or a portion thereof and is so arranged in relation to the companionelecrode that the arc can be quenched by permitting the rapid escape of or causing the removal of, hot gases from the vicinity of the arcroot and arc-path along said passage and wherein means for separating the electrodes to break circuit are so arranged as to effect such separation to and not materially beyond a limiting distance substantially such as hereinafter described and preferably at a velocity substantially not less than that hereinafter indicated.

The above features and other features of the invention pointed out in the appended claiming clauses will be evident to those skilled in the art from the .following description, given by way of example, of constructions of circuit-breakers according to the invention.

In the accompanying drawingsz- Figure 1 is a side elevation, mainly in section, of the upper part of one construction of circuitbreaker according to the invention;

Figure 2 is a side elevation, mainly in section, of the upper part of a second construction of circuit-breaker according to the invention.

Figures 3, 5, 6 and 8 are vertical sections showing modified forms of electrodes.

Figure 4 shows a switch with a modied operating mechanism.

Figure 7 is a `plan View of the spider shown in Figure 6.

Figure 9 is a section on the line 9 9 of Figure 8.

Referring rst to Figure 1, the contacts or electrodes 10, 12 are situated Within a cylindrical gas-tight container 14 which may be provided with an interior lining 16 of quartz or other suitable material as shown. The upper end of the container 14 is flanged and is closed by a cover 18 of bakelite or other insulating material, seated on the flange, the parts being held together by bolts 20 passing through the flange and cover and also through a ring 22 interposed between the nuts of the bolts and the cover 18. The interior lining 16 of the container is continued by a ring 17 of quartz or the like placed between the container wall and an upper and tubular part 13 to which, as hereinafter explained, the electrode 12 is connected, packing washers 19 of asbestos or other suitable material being located above and below the outer margin of the ring 17 as shown in Figure 1. The cover 18 at its centre has an aperture through which passes the lower end 24 of a vent pipe 26, which end abuts against the bottom of a recess formed in the tubular part 13. The pipe 26 and the part 13 are secured to the cover 18 by studs 28 screwed into the part 13 and passing through the cover and through a iiange 30 on the pipe, nuts on the studs serving to clampthe parts securely together. As the pipe 26 is of metal-preferably copper-and is in electrical contact with the part 13, the lead from the circuit to be controlled by the breaker, may be connected with any suitable part of the pipe, or any other part of the apparatus in metallic contact with the pipe.

The vent pipe 26 carries at its upper end a valve-chamber 32, the pipe and chamber being secured together by bolts and nuts 34, the former 'passing through a flange formed on each of these parts. In certain cases it may be necessary or desirable to provide the vent pipe at a convenient position along its length with a grid-member to prevent metallic beads or the like from the electrodes from reaching the valve chamber or its valves. conveniently take the form of a metallic ribbon Wound into a flat spiral and attached to the interior of the pipe with its axis substantially in alignment with the pipe axis as .shown in Figures 8 and 9. The moving members 36 of the valve, after the breaker has been closed as presently to be described, are held on their seatings 38 by a toggle 40 which is maintained, at such time, in the position shown in Figure 1 by an endwise movable rod 42. This rod may be operated by any suitable means, those shownwhich are to be regarded as diagrammatic in characterinclude a second toggle 44. Springs 46 and 48 acting upon lthe valve members 36 and the rod 42, respectively. move the members This grid-member may quickly from their seatings immediately the toggle 44 is broken The valve-chamber, as shown, is formed for convenience of assembly in two portions bolted together, and it carries at one side a frame or housing 50 for the toggle 44 and its associated parts. The rod 42 which is connected with one member of the toggle 44 passes through a gland 52, while the other member of this toggle is connected to a short rod 54 which is guided in the housing 50 and is backed up for purposes of adjustment by an adjusting screw 56. Bolted upon the flanged upper end of the valve-chamber 32 is an extension pipe 58, the upper end of which has attached to it, a flaring mouth-piece 60.

The upper electrode 12 comprises a cylindrical body built up of separate longitudinally extending sections-four, in the present instancewhich are yieldingly held together by spiral springs 64 seated in shallow recesses in the sections. The sections are movably supported on the part 13 by a ring 116 screwing into the latter and engaging notches formed in the sections. For the purpose of assembly of the parts this ring 116 is formed in two portions. Good electrical contact between each section and the part 13 is ensured by a connection 118 fastened to the section and gripped against the body 13 by the ring 116. As shown, a washer is inserted between the part 13 and these connections.

The lower electrode 10 (which is the moving member in this construction) is a solid cylindrical member with a rounded upper end adapted to enter between and slightly separate the sections of the upper electrode when the breaker is closed, the interior lower edge 15 of the contact surface of each of the said sections being rounded, as shown, to assist in this action. The operating rod 66 of the lower electrode 10 passes through a gland (not shown) in a cover which closes the bottom end of the container 14, the operating rod being a good electrical conductor which is in electrical connection, through the cross-bar 67, to the outgoing lead (not shown). This cover and the parts adjacent it may be similar to the parts 17, 18, 19, 22 already described in` connection with the upper end of the container, the gland aforesaid in the lower cover taking the place of the member 13 in the upper. At a convenient location in the container there is provided an inlet for the gas which is to be used in the extinguishing of the arc., The rod 66 is operatively connected by means including a rod 68 with the toggle 44 which as above described forms part of the control mechanism for the valve-members 36. in two parts insulated electrically the one from the other as shown diagrammatically at 69 in Figure 1) at its upper end has a attened portion having two spaced pins 70, 72 which act,

respectively, to make and break the toggle 44 upon endwise movement of the rod 68.

Figure 1 shows the breaker in the closed position, that is to say, with the electrodes 10 and 12 in contact, and the valve-members 36 upon their seatings, thus closing the exit from the container 14 which, consequently, is filled with gas under pressure. In the opening operation of the breaker, just after the electrode 10 commences its downward movement and before it breaks ccntact with the electrode 12, the toggle 44 is broken by the pin 72 on theV downwardly-moving rod 68. The springs 46 and 48 then quickly open the valves 36 to their full extent, allowing gas from the container 14 to ilow through the passage 25 This rod 68 (which is formed'within the electrode 12, the part 13, the vent pipe 26, valve-chamber 32, and the pipe 58 from whence itl escapes by way of the mouthpiece 60, the gas flowing over the surfaces oi' the electrodes in between the sections of the electrode 12 which at this time, owing to the presence of the electrode within them, are slightly sepa- A separation of the electrodes after the setting up of the arc to a distance not exceeding some 2 cms. (when the pressure is in the neighborhood of 5,500 r. m. s. Volts) 'Ihis may be done by the means shown diagrammatically in Figure 4 in which the operating rod 10 of the gasblast switch 183 is controlled by a cam 187 which is rotated in the direction of the arrow to open the switch. It will be seen that the shape of the cam is such that a pause is introduced in the opening movement of the switch, during which pause the arc is ruptured, by a blast of gas from the reservoir 188. In Figure 4 the electrodes are shown in the position of the commencement of pause as in Figure 2.

In vthe closing operation, the valve last mentioned is first opened and, prior to the engagement of the electrodes 10 and 12, gas is supplied to the container 14 from whence it issues along the passage above indicated. The electrode 10 subsequently makes contact with the electrode 12 thus completing the circuit controlled by the breaker, and nally the pin 70 on the now ascending rod 68 makes the toggle 44 and closes the valve-members 36 upon their seatings 38, thus cutting off the gas blast.

It may here be mentioned that an apparatus constructed with single break in accordance with the disclosure of Figure 1 has been found, when operating with hydrogen at 4 atmospheres absolute pressure and 6000 cubic inches per second flow at the density 4, to be able to break circuit regularly in under a cycle of arcing. and to release in the arc only about 1/5 of the energy that would be released by a single break switch operating at the same velocity of contact separation, viz: about 1'75 centimetres per second in oil under the same circuit conditions. A unit of this kind operating with single break has cleared over 25,000 K..V. A. at 6600 volts, so that six units comprising the six breaks of a double break triple pole switch should be capable of handling upwards of 150,000 K. V. A. at say 22,000 line volts r. m. s.

In Figure 1, in which the parts 10, 12 and 13 and the diametral dimension of the part 14 are shown in substantially their correct relative proportions, the diameter of the electrode 10, which in the construction under consideration is formed of copper, -is substantially seven-eighths of an inch.

It will be noted that the valvesl 36, 38 although they are connected electrically with the electrode 12, are in a position in which they present no surface from or to which an arc will pass or form.

Referring next to Figure 2, wherein is illustrated another construction of breaker according to the invention, the apparatus comprises a cylindrical gas-tight container 100 having atits upper end a body 102 of porcelain or other suitable .nsulating material which is supported by a metallic ring 104 bolted to the container and cemented into a recess formed for it in the body 102. A flanged part 105 secured to the body 102 by the aid of studs 106 cemented into the latter, supports a vent pipe 108 provided at its upper end witha gas-cooling mouth-piece 110 similar to the mouth-piece 60 of the construction of Figure 1. A cowl 111 of bakelite or other insulating material covers the upper part of the apparatus to which it is secured in any suitable manner. This cowl, which extends above the upper end of the mouth-piece 110, has an opening 113 to permit escape of the gases and also a hole 115 through which extends a lead 117 electrically connected with the part 105. The part 105 carries the upper and stationary electrode 12 which is the same as and is supported in a manner similar to the electrode 12 of Figure 1, and need not therefore again be described.

The lower electrode 10 is carried upon the upper end of a rod 124 arranged to slide within a metallic sleeve 126 supported in an insulating member 128-such as a moulding of bakeliteitself supported in the container 100 by lugs 130 on the moulding resting upon and bolted to corresponding lugs 132 on the container. This moulding, for convenience, is formed in two portions, i. e. it comprises a portion 134 screwed on to the portion 128.

In the neighbourhood of the electrodes the container is provided with a lining, in this case a triple lining composed of two layers 136 of quartz separated by a layer 138 of asbestos. The lining at the upper end of the container is continued by a quartz ring .140 between which and the triple lining on the one side and the part 105 on the other asbestos packing washers 142 are placed. The upper part of the moulding 128 is protected by a quartz cover 144 which acts as a deflector for any metallic beads which may happen to be formed from the electrodes during the rupturing of the arc. Such beads, should they be formed, will thus be deflected towards the container wall and fall into the pocket 169 provided and thus will be unlikely to interfere with the working of the valve now to be described.

Bolted` to the bottom of the container 100 is a valve-chamber 146. The valve seating member 148 is secured to the top of this chamber and preferably includes seating washers 150, 151 of leather or other suitable material. The moving member 152 of the valve is attached to the rod 124 that carries the electrode 10, the connections between the member and rod including a sleeve 154, of insulating material such as Vbakelite, clamped firmly to both of these parts by the aid of a nut 156 and washers 158, 160 and acollar 162 fast on the rod. Preferably the washer 160 is made of insulating material such as bakelite. A washer 164 of leather or the like is interposed between the valve-member 152 and a head 166 on the sleeveto form a gas-tight joint, and a similar washer 168 is, for the same purpose, interposed between the member 152 and the washer 160. The valve member for purposes of construction is made in two portions which are held pressed together by the nut 156 acting through the washers 160, 162 and 164 against the collar 162. Washers 1'70 of leather or other suitable material are inserted between the two portions of the valve part 152 to form a gas-tight joint. A cylinder 171, preferably of wood or other light-weight material, is held between the two portions of the valve part 152 and is preferably shaped on its outer surface so as to approximate to stream-line" form to facilitate flow of gas through the valve. It will be noted that the valve-member 152 and its seatings are electrically excluded from the circuit of the arc.

Figure 2 shows the position of the parts when the electrode 10, in its movementof separation from the electrode 12, has arrived at the. preferred distance of travel above explained. In the construction of Figure 2, as described above, the electrode dwells in the position in which it is shownthat is, at the preferred gap-and then continues its downward movement until the valve member 152 is closed upon the upper seating of the member 148.

Now consider the electrodes in their fully open position after such further travel, at which time the valve member 152 is shut down on its upper seating and the interior of the container 100 is at atmospheric pressure. Immediately the breaker is operated to close the circuit, the rising rod 124 which is connected at its further extremity to the outgoing lead (not shown) lifts the valve member 152 from its upper seating allowing gas to flow from the valve-chamber 146 into the container 100, from whence it-escapes through the passage formed in the electrode 12 and in the parts 105, 108 and 110. The electrode 10 next engages its companion 12 and closes the circuit, and in so doing slightly spreads apart the sections of which the electrode 12 is made' up. Finally, the valve-member 152 meets its bottom seating thus cutting off the gas from the chamber 146.

In the opening of the circuit the valve member 152 rst moves from its bottom seating and gas Hows from the chamber 146 to the chamber 100, from whence it escapes through the slits between the spreadsections of the electrode 12, into the passage aforementioned, finally passing out of the apparatus by way of the mouthpiece 110. the electrode 10 moves downwards it will be evident from the construction that just before it parts company with the electrode 12 the valve part 152 gives full opening to the now of gas at the seating 148. The electrodes next separate to the preferred gap, and the arc formed thereby is quickly quenched by the flowing gas the velocity of which is now such as to bring this about. The electrode 10 is now in the position illustrated in Figure 2 where it pauses briefly until the arc is extinguished. This cessation of movement may be brought about by a cam motion, a latch operated by a series coil or other suitable device (not shown), or by means such as cams or dash pots, for example by a dash pot and piston, as in Figure 4, arranged on the lower part of the electrode stem and in a chamber below the lower valve in Figure 2.

The duration of this pause, when not governed by a series-coil-operated device (which latter is so arranged as to stop or delay continuation of movement until after the current has ceased) should preferably be at least equal to one period of the frequency of the system on which the circuit-breaker is operating.

After this pause, the electrode 10 continues on its downward movement until, finally, the valvemember 152 is brought down upon its upper seating and the supply of gas to the container 100 is cut off. The construction of valve shown is such that, from a moment prior to electrode separation until after the period of pause, the valve 152 gives full opening tothe gas flow through the seating 148.

With regard to the dimension of the preferred gap, if the limiting dimension below which the arc can reform after passing through zero is found to be very small, say under one centimetre as in the present case, it is advisable to arrange for a slightly greater gap to provide for emergencies and to allow for a factor of safety. In the present instance, one and a half centimetres was found suincient, to produce which degree of separation the electrode 10 has to travel some two centimetres on account of its curved surface and of the curved surface of the electrode 12.

It should be the aim of a designer of a circuitbreaker according to the present invention to provide for the introduction of the aforesaid preferred gap as quickly as possible in the breaking of the circuit. To this end the speed of separation of the electrodes, should be the maximum obtainable with the particular apparatus under design and as a guide to a lower limit it may be mentioned that this speed preferably should be at least high enough to introduce the preferred gap within a time-period equivalent tothat occupied by one half cycle of the frequency of the system on which the circuit-breaker is to operate.

If for constructional reasons, the high velocity of electrode-separation thus required for high voltages, and the consequent longer gap, is not readily obtainable, the gap may be formed in more than the one half-cycle.

From the drawings it will be evident that the sleeve-like depending portion 23 of the upper electrode 12 (which preferably extends downwards a distance substantially equal to the preferred distance of Contact separation hereinbefore mentioned) forms, in conjunction with the lower electrode 10, a portion of the passage aforesaid along which the gas ow takes place, this portion 23 serving to guide the gas on its way to the passage 25, over the surface of the electrode 10, the gas stream thus guided surrounding the arc which is thereby compelled to remain within the stream throughout the arcing period.

To aid in the prevention of sparking and also to ensure that the main gas flow takes'place in close proximity to the surface of the contact 10, the inner wall of thedepending portion 23 may be lined .with quartz or the like as shown at 200 in Figure 3 either for part or for the whole of its length.

The provision of an insulating sleeve of the above type may be specially advantageous on extra high tension work where if unlined, the depending portion 23 would have to be of proportionally greater diameter than that shown, in order to prevent spark over between the wall of said portion and the electrode 10. -In the above connection it will be noted that the greater the diameter of the depending portion the greater the amount of gas which would escape over the surfaces of the depending portion remote from the arcing surface of contact 10.

If desired, the electrode 10 before referred to (particularly in cases where relatively heavy currents are to be carried by it) may be pierced to provide, in this electrode also, facility for the flow of the gas or gases when the electrodes are in engagement. For instance, this electrode may be pierced from its apex by a bore extending downwardly axially of the electrode for some distance and then leading out to the side of tile electrode by one or more passages through which, when the electrodes are in contact, gas may flow into and then up through the said `bore (see the chain-lines on the electrode in Figure 2).

Although the particular form of electrode 12 herein described has been found to give very good results, it is to be understood that the invention is not limited to such a construction: for instance, instead of being shaped at its lower end as shown in Figures l and 2, the electrode may have a downwardly-daring mouth as shown in Figure 5, which if desired, may be of stream-line shape'. In a further construction of these electrodes as shown in Figure 6 the lower electrode may be provided with sections 201 similar to those of the upper electrode 12. These sections will be secured to the main portion of the lower electrode in a similar manner, that is tosay so as to be capable of moving towards and away from one anothenand will be provided with' springsl tending to press them together. In the main body of the lower electrode, ylateral passages 202 will be formed leading into th'central passagev formed between the yielding sections just described. The upper electrode, in this case, will comprise a central cylindrical portion 203 (supported by a central spider 204, Figure 7) rounded at its end to enter readily between the sections 201 oi.' the lower electrode, and surrounding this central portion 203 and also the sections of the lower electrode when the parts are in engagement, there will be a cylindrical body` 12 which itself may be formed in sections like those of the electrode 12 (Figures 1 and 2) which sections will be pressed together by springs. This central cylindrical portion 203 and the cylindrical body 12 will be electrically connected together. The cylindrical body 12 of the upper electrode may be provided with a downwardly extending and wider or ared portion as in the contact 12 Figures 1 and 2; the central cylindrical portion of the upper electrode would not, however, be extended below the restricted portion of the passage in the upper electrode. In this construction, when the electrodes are in engagement gas will be able to flow through the central passage in the lower electrode and from thence through the slits between the yielding sections of this electrode into and along the passage formed between the central cylindrical portion and the cylindrical body of the upper electrode. If this latter electrode has its cylindrical portion formed of sections as aforesaid gas will also be able to flow into the passage in this electrode by way of the slits between these sections.

The above construction has the feature that the cross-sectional area of opening and the distance between the substantially equipotential inner and outer walls of the passage can be xed independently of each other, which may be of considerable importance in practice in extra high tension work where the currents tend to be relatively small, necessitating small spacing between equipotential walls to prevent bowing within said passage and where at the same time a powerful gas blast (which cannot be attained in a tube of the same diameter as the above passage width) may be necessary.

To prevent liability of the moving electrode 10 rebounding in the opening operation of the breaker, there may be provided any suitable meanssuch as a spring controlled latch-which acting on a part of the operating mechanism will permit it to move in the required direction to open the breaker but will prevent accidental movement in the opposite direction, which might so shorten the gap between the electrodes 12 and 10 as to allow spark over, and restarting of the arc.

In both the constructions illustrated, the arc is struckfrom an inner wall of a passage 25 formed in one of theelectrodes and is quenched by a ilow of gas alongsuch passage. Extension of the arc, as for instanceby bowing or looping within the passage, is preventdbylthe fact that the arc is surrounded by substantially@quipotential surfaces of high conductivity whichtend to short-circuit any portion of the arcwhich coinmences to bow or loop. In order to obtain the best results in this respect is would appear that the diameter of this passage 25 should not materially exceed a dimension of the order of twice the diameter of an arc crater or burn formed by an arc between contacts during a whole cycle of arcing. For any given apparatus, this can be preliminarlly measured in a different apparatus (which should have, however, electrodes of the same mass as those to be used in the given apparatus) by using a low voltage current of the same value as that to be dealt with in the given apparatus and taking care that conditions of gas, gas pressure and time of arcing are the same in both cases. If, however, a passage based upon such measurement proves to be too small to allow of an adequate velocity of the gas flow, a passage large enough to permit the required velocity can be used, and a metallic grid as shown at 212 in Figures 8 and 9 (or the equivalent in the form of a central cylindrical portion 203,

Figure 6 extending longitudinally of the passage) inserted in the passage near the arcing location, the grid spaces or the gap between the central cylindrical portion 203 and the surrounding wall 12 of the passage, being each of the size obtained from the measurement above mentioned. When such a grid as 211 is used, care should. be taken to ensure that the length of the passage between the grid and the bottom end of the passage i.- e. the locality of contact separation, is kept, as short as possible to avoid any tendency for lengthening of the arc which might occur with a ylarge passage as aforesaid. A grid comprising a central cylindrical partition as aforesaid can be arranged to extend to the point of contact separation if the bottom contact is of the female type. This grid or central partition or portion will be in electrical connection with the electrode l2.

It is to be understood that the `constructions herein described are designed and intended to be set to minimize extension of the arc under short-circuit conditions, that is to say, to enable the worst case that can arise to be dealt with successfully. Consequently, at loads smaller than loads on short-circuit there may be some lengthening of the arc.

Care should be taken that connecting pipes land valve openings are of sufficient cross-sectional area as to allow of the requisite gas pressure being set up in the chamber 14 or 100 before the separation or before th'e closing of the contacts takes place. And to the same end, the volume of chamber 100 should be kept relatively small. tioned that the internal cross-sectional area of the 'vent pipe 26 or 108 should at least be the same as that of the passage through the upper electrode l2. Further, passages and openings through which gas flows should, where possible, conform to streamline shape.

Experiments have shown that to obtain the best results it is advisable to limit the travel of In this connection, it may be men' separation of the electrodes after the setting up of the arc to a distance not exceeding some two centimetres (when the pressure is in the neighbourhood of 5500 r. m. s. volts) and, after the arc has been quenched and before the gas flow drops below a predetermined velocity as aforesaid, to continue the downward movement of the electrode 10. A pause may be made at the aforesaid limiting distance'by means shown in Figure 8, which illustrates the lower portion of the casing 146. The stem 124 passes through an insulating gland 208 in the base of the casing 146 and is carried by the usual moving means. vshown as a cross-bar 209. Supported by a light spring 210 is an inertia mass 207 which will be struck by a part 211 secured to the stem 124 when the lower electrode reaches the position shown in Figure 2.` In overcoming the inertia of the mass 207, a pause is enforced in the downward movement of the electrode 10.

In view of the fact that it may be difficult always to estimate the velocity of gas flow attained in a system of piping subject (under factory conditions) to additions and alterations, it is advisable that the volume of the valve chest 146 (Figure 2) or a reservoir opening immediately into it should be so proportioned in regard to the volume of the chamber that sufficient gas is immediately available for raising the pressure in the chamber 100 to the required amount before contact separation takes place.

We claim:

1. An electric circuit-breaker for. alternating electric currents comprising a pair of relatively movable electrodes one of which has a passageway formed in it, means forI establishing a flow of gas wiping a surface of the other electrode and into said passageway, and operating mechanism for separating the electrodes at a definite speed, the gas entrance end of the passageway extending and spreading outwardly to form an inwardly hollow mouth extending beyond the region of least gap between the electrodes throughout the period from commencement of arcing to the first attainment of substantially zerovelocity of electrode separation to guide the gas current inwardly to the passageway to prevent the arc from leaving, on the entry side, the main stream of gas flowing into the passageway.

2. An electric circuit-breaker for alternating electric currents comprising a pair ofrelatively movable electrodes one of which has a passageway formed in it, means for establishing a flow of gas wiping a surface of the other electrode and into said passageway, and operating mechanism for separating the electrodes, the gas entrance end of the passageway extending and spreading outwardly to form an inwardly hollow mouth to guide the gas current inwardly to the passageway and to prevent the arc from leaving, on the entry side, the main stream of gas flowing into the passageway, and the operating mechanism and electrode shape being such that the end of the moving electrode remains within said mouth throughout the period from commencement of arcing to the first attainment of substantially Zero velocity of electrode separation.

3. An electric circuit-breaker for alternating electric curfents comprising a male electrode, a female electrode having a passageway for the removal of hot gases, means for establishing a flow of gas wiping a surface of the male electrode and into said passageway, and operating mechanism for separating the electrodes, the gas entrance end of the passageway extending and.

spreading outwardly to form an inwardly hollowY mouth to guide the gas current inwardly to thi'V passageway and to prevent the arc from leaving, on the entry side, the main stream of-gas flowing into the passageway, and the operating mechanism and electrode shape being such that thtend of the male electrode remains within said mouth vthroughout the period from commencement of arcing to the first attainment of substantially zero velocity of electrode separation.

4. An electric circuit-breaker for alternating electric currents comprising a pair of relatively movable electrodes one of which has a passageway formed in it, a continuation passageway extending away from the region of commencement of arcing towards the inflowing current of gas and of larger cross section than the f1rst named passageway, means to cause a flow of pressure gas at high velocity through said continuation passageway, towards and through the first passageway, said fn'st named passageway having a surface spreading outwardly from its gas current entrance on all sides to meet the boundary surface of said continuation passageway and forming together with said surface guiding means to guide said gas flow to prevent the arc from leaving, on the entry side, the main stream of gas flowing into said passageways.

5. An electric circuit-breaker for alternating electric currents comprising a pair of relatively movable electrodes one of which has a passageway formed in it, a continuation passageway extending away from the region of commencement of arcing towards the inflowing current of gas and of larger cross section than the first named passageway, means to cause a flow of pressure gas through saidV continuation passageway and through the first named passageway, thc passageway, the continuation passageway and the counter-electrode all being of circular cross section and coaxial and the said first named passageway having a surface spreading outwardly from its gas current entrr'ice on all sides to metu the boundary surface of said continuation passageway and forming guiding means to guide said gas flow so that the counter-electrode is symmetrically immersed in` the gas current and the arc is prevented from leaving, on the entry side, the main stream of gas flowing into said passageways.

6. An electric circuit-breaker for alternating electric currents comprising a male electrode, a female electrode having a passageway for the removal of hot gases, an extension of said female electrode having a 'continuation passageway formed therein through which said gases ow bei fore reaching the rst named passageway, an annular insulating member which fits the gas entrance mouth of said continuation passageway, and surrounds the male electrode and in which the cross sectional area of the space between the inner wall of said insulating member and the surface of the male electrode from which said inner wall is on all sides substantially equidistant is smaller than the area of the space between the walls of said continuation passageway and the surface of the male electrode. and means for providing a flow of gas into and through said insulating member towards and through the aforesaid outlet passage of the female electrode, said insulating member and extension constituting guiding means to guide the gas stream to prevent the are from leaving, at the entry side, the main stream of gas owing into the passageway.

7, All electric circuit-breaker for alternating electric currents comprising a pair of relatively movable electrodes one of which has a passageway formed in it, means for establishing a flow of gas wiping a surface of the other electrode and into said passageway, means to guide the gas stream to prevent the arc from leaving, on the entry side, the main stream of gas flowing into the passageway, and circuit breaking means acting rst to separate the .electrodes to a preferred distance, thereafter to retain them substantially at this separation for a short time and then to effect afurther separation before the aforesaid gas stream ceases flowing.

8. Anfelectric circuit-breaker for alternating electric currents comprising a male electrode, a female electrode having a passageway formed in it for the escape of hot gases, conducting means situated in said passageway, at such a distance from the initial arcing position as just to allow full closureV of the counter-electrode, the openings past said conducting means being such that at least one dimension thereof shall be not greater than twice the diameter of an arc crater, such as an arc would form during a complete cycle under the same conditions relatively to-flow of gas, gas pressurel and duration between electrodes through which the maximum current for which the breaker is intended flows and which have the same mass as the electrodes of the breaker, and means for establishing a ow of gas across a surface of the male electrode and into said pasageway.

9. A circuit breaker for alternating current comprising in combination a member having a passage the walls of which constitute an outlet portion, a relatively narrow throat and a wider mouth portion protruding from said throat, a conducting member in the throat portion surrounding the passage and electrically connected with one of the contacts, the wider mouth portion being laterally spaced away from the other contact when in its closed position, means whereby a flow of fluid under pressure is passed through said passage, the said contacts being separable within the mouth portion and so situated that the uid entering lthe mouth to pass through the throat portion will pass through the space between the contacts and will wipe over their arc bearing surfaces at rhigh velocity throughout the period of arcing, said flow being in such a direction as to prevent that portion of the arc stream lying within the portion of the fluid stream flowink towards the throat portion from escaping said portion of the flowing uid and jumping to `the outside of the entrance to the entrance mouth portion.

10. A circuit breaker for alternating current comprising in combination a member having a passage, the walls of which passage constitute an outlet portion, relatively narrow throat and a Wider mouth portion protruding from said throat, a conducting member in the throat portion surrounding the passage, electrically connected with one of the contacts, the wider mouth portion being laterally spaced away from/the other contact when in its closed position, means whereby a ow of helium under pressure is passed through the said mouth and then into and through the said throat and outlet portion of the passage, the said contacts beingl separable within the mouth -portion and so situated that the helium entering the mouth to pass through the throat por tion will` pass through the space between the concomprising in combination a member having a passage, the walls of which passage constitute a relatively narrow' throat and a wider mouth portion protruding from said throat, a conducting'member in the throat portion surrounding the passage and electrically connected with one of the contacts, the wider mouth portion being laterally spaced away from the other contact when in its closed position, means whereby a flow of fluid under pressure is passed through said passage entering by way of the aforesaid mouth portion, the said contacts being separable within the mouth portion and so situated that the fluid entering the mouth to pass through the throat portion will pass through the space between the contacts and will wipe over their arc bearing surfacesv throughout the period of arcing, the first-mentioned passageway being so shaped that it provides a walled path. of increasing crosssection through which fluid is allowed to escape after passing through said throat.

12. An electric circuit breaker for high voltage alternating current comprising -a pair of relatively movable electrodes, means for controlling their separating movement, a passageway (with a narrower portion) of which one electrode forms at least a part, means for establishing a flow of fluid washing a contact-making surface of the counter electrode and through said narrower portion, an inwardly hollow entrance mouth protruding from said contact-making surface for uid entering said mouth and narrower portion, said mouth extending and spreading outwardly beyond any point that becomes, during a period of about one cycle from the commencement of arcing, the termination of a shortest line between the separating arcing surfaces of the electrodes, said mouth forming with the surfaces of the counter electrode, outer and inner bounding walls of an annular entrance path of crosssection narrowing towards the aforesaid space of least gap.

13. An electric circuit breaker for alternating currents comprising a pair of relatively movable electrodes between which an arc is formed, one of which is hollow, a coaxial central pin shaped insertion of conducting material in said hollow electrode, a counter-electrode insertable within the aforesaid hollow electrode and recessed to pass along said projection, a fluid passageway being aorded between the inner walls of the hollow electrode and the adjacent walls of the central insertion and a passageway being provided from the bottom of the recess in the counter-electrode extending away from the central insertion to the outside of said counter-electrode, one of the coaxial cylindrical surfaces of said recessed counter-electrode forming a contact making surface and its other surface being spaced away from the adjacent wall of the aforesaid fluid passageway to provide free passageway therebetween for uid at al1 stages of relative movement of the electrodes, means for producing a ow of fluid wiping a surface of the coun' ter-electrode and into the passagewayin the hollow electrode, and guiding means to guide the fluid stream to prevent the arc from leaving, on .the entry side, the main stream of uid flowing into the hollow electrode and passageway.

lll. An electric circuit breaker for alternating currents having a structure comprising a containerfor fluid, a walled vent passageway therefrom having a throat portion and an extended exhaust portion Widening therefrom to a region of generally lower pressure, electrodes separable afterpassing through a value of zero current but such that the said least gap between the electrodes lies substantially within the region scoured by the high velocity f low of fluid, means by which the gap is maintained substantially at said length for a short time and means to effect an acceleration in the lengthening of the said gap for a short time thereafter.

15. An electric circuit interrupter comprising a fluid container embodying a passage for exhaust of uid therefrom, the passage being narrow at least in the region of arcing, electrodes separable in the neighborhood of said narrow portion within said container, means to discharge a blast of fluid through said narrow portion and exhaust passage and a walled approach extending to and connecting with said narrow portion to direct said discharge between said.

electrodes substantially the whole of the blast path lying across the gap between the electrodes,

said electrodesbeing so placed in relation to the walls of the passage that substantially the whole arc path within the container is scoured by said discharge, and means operative in the neighborhood of the arc gap within said passage to obstruct extension of the arc by said blast while allowing easy exhaust for said blast uid.

16. A high tension circuit breaker comprising a pair of electrodes, one of said electrodes having a passageway forming a contact making portion and a walled exhaust outlet widening therefrom, within which passageway the other electrode is disposed in the closed/position of the interrupter, the contact making surfaces of said electrodes coacting in the neighborhood of the throat of said passage, means to direct a blast of uid under pressure through said passageway and conducting means electrically connected to the electrode having the passageway to which conducting means an arc 'can flow, thesaid conducting means being situated beyond the initial contacting position in a region washed by the blast of expanding uid flowing within the walled exhaust outlet, the electrodes being so placed in relation to the fluid blast that one end of the arc upon separation of said Contact making surfaces is blown on to the tip of the inner electrode and the other end is blown on to the said conducting means.

WILLIS BEVAN WHITNEY. EDMUND BASIL WEDMORE.

CERTIFICATE 0E CORRECTION.

Patent No. 1,928, 470.

September 26, 1933.

WILLIS BEVAN WHITNEY, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, I

line 149, beginning with "Experiments" the numeral "162" read 168; page 5, strike out all to and including "electrode l0.

line 1 45, for

" in line 20, page 6; and that thesaid Letters Patent should be read with these corrections therein that the same may conform to the record of the case in Signed and sealed this 24th day of July,

(Seal) the Patent Office. A. D. 1934.

Bryan M. Battey Acting Commissioner of Patents, 

